Novel reductones and methods of making them



.phenolindophenol, as well as silver, mercuric, cupric or NOVELREDUCTONES AND METHODS OF MAKING THEM 5 John E. Hodge, Pe0ria, 111.,assign'or to the United States 'ofltAurmerica as represented by theSecretary of Agricu e No Drawing. pplication .lune 2, 1955 Serial No.512,915

16 Claims. or. 260-211) (Granted'under Title 35, U.S. Code (1952), see.266) A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power-to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to new chemical compounds and to methods formaking the same. It relates more particularly to certain novelreductones and to methods for making them by converting reducing sugarsthrough the glycosylamines or the corresponding Amadori rearrangementproducts of these glycosylamines.

The term reductones as used in this application refers to the class,of'unsaturated, dior poly-enolic organic compounds which, by virtue ofthe arrangement of the enolic hydroxyl groups with respect to theunsaturated linkages, possess characteristic strong reducing power.These compounds will readily reduce iodine and dichloroferric salts inacidic aqueous solutions. Compounds which are known in the literature tohave the above properties are: ascorbic acid (vitamin C), reductic acid,glucic acid (triose-reductone, gluco-reductone), dihydroxymaleic acid,ot-ot'-dihydroxymuconic acid, pyrogallol and .also (according to oneauthority) hydroquinone .(p-dihydroxybenzene), catechol(o-dihydroxybenzene), adrenaline, p-aminophenol and o-aminophenol. Insome compounds, such asthe last two named, an amino group,

a mono-substituted amino group or an imino group'may replace one or moreof the enolic hydroxyl groups without affecting the characteristicreducing behavior of the compound. Compounds of this class reducemetallic ions, such as silver, mercuric, ferric, cupric in acid as wellas in alkaline solution and have found wide-spread use as reducingagents, antioxidants, photographic developers and medicinals. v

The new compounds of this invention are derived from sugars, especiallyglucose, although other 6 carbon sugars are included, as will beapparent from the following specification.

The glycosylamines which may be used as starting materials in theprocess of this invention and the corresponding Amadori-rearrangedproducts have the following typical structural formulas: 60

yranose ring tor'm) (open-chain form) 2,936,308 Patented "May 10, 1-960radicals R may be joined by an alkylene chain, such 2 as in thepiperidyl radical vor an oxygen interrupted alkylene chain such as themorpholinyl radical. The radicals R may be substituted by variousradicals or substituents which are inert. One of the radicalsyR, mayalso be hydrogen. Examples of particular substituents are ethyl, propyl,butyl, hexyl, hydroxymethyl, hydroxypropyl, tolyl, benzyl, phenyl andthe like.

-As disclosed in my copending application Serial Number 256,587, filedNovember 15, 1951, now US. Patent No. 2,715,123, the Amadorirearrangement maybe carried out by heating the glycosylamine in thepresence of a secondary amine and a compound which possesses 'an activehydrogen atom linked to a carbon atom in the alpha position to anunsaturated linkage, said compound being non-acid in character. Asfurther disclosed. in said application, examples of such compounds aremethyl malonate, ethyl malonate, ethyl acetoacetate, ethyl cyanoacetate,phenylacetone, fluorene, and the like.

I have discovered that the glycosylaminesor their corresponding Amadorirearrangement products maybe converted by heating to novelaminoglycose-reductone products which possess exceptional reducingpower,.antioxidant properties, and are particularly adaptable as oxygenscavengers and antioxidants. I have further discovered that my novelreductones may be prepared directly by heating a hexose reducing sugarand a secondary amine (corresponding to the N-substituents of theforegoing structural formula). hastened by the presence of areductone-forming catalyst which will be described in detailsubsequently. This latter method affords a direct synthesis, andpossesses the attendant advantage of avoiding the necessity for theseparation of either the glycosylamine or its rearrangedaminodeoxyketose product. The foregoing methods .are each illustrated inthe examples.

The phenomenon of the formation of the novel 'reductone is characterizedby the chemical removal of two molecules of water from one molecule ofthe glycosylamine or the rearranged aminodeoxyketose product. When thehexose reducing sugar and secondary amine are used as startingmaterials, a total of three molecules of water are removed. It'istherefore advisable to conduct the conversion in an environment that issubstantially free of water. The presence of minor amounts of water,however, is not detrimental.

it is not necessary to provide a reaction medium, as the reactionproceeds upon heating the dry materials. The reaction will proceedspontaneously, though at a slow rate, upon permitting the N-substitutedglycosylamine '01- its rearranged aminodeoxyketose product to stand atroom temperature. To provide reasonable reaction times (10-24 hours)without too much unwanted decomposition, the reaction temperatures maybe held within the range 6090 C. The specific examples illustratereaction times within this temperature range for the formation of thereductones in 6 to 24 hours, and show that shorter times of about 2hours are suflicient'at higher temperatures. They also show that thereaction proceeds very slowly unless heated above room temperatures (25C.). 1

I prefer to employ an aldohexose, such as D-glucose, D-galactose orD-mannose, or a ketose, such as D- fructose or L-sorbose as thecarbohydrate starting material.

The amine starting material may be any secondary amine, includingaliphatic, aromatic, aralkyl, alicyclic and heterocyclic aminesandaminoacids. "Colorless or lightly colored macrocrystalline productsare obtained,

The reacgion isv 'results, yet the time For the sake of convenience andexpedience, I prefer to conduct the reaction in an inert organic solventsuch as ethanol, methanol, and the like. Other solvents within the scopeof this invention are pyridine, liquid ammonia, acetone, ether anddioxane.

As previously mentioned, the reaction is hastened by heating in thepresence of reductone-forming catalytic agents. These agents are themineral acids, such as phosphoric and boric, carbonic acid, organicmonoand polycarboxylic acids or their amine salts such as acetic acid,piperidine acetate, morpholine acetate, ethylamine acetate, malonicacid, piperidine malonate, dibutylamine malonate, propionic acid,propiona-tes, benzoic acid, benzoates, phthalic acid, phthalates,succinic acid, succinates, citric acid, citrates, glycine, asparagine,glutamic acid and the like. Those acid agents which can exist inanhydride form may also be used in that form, since the water generatedby the reaction will hydrate them. All of the foregoing catalysts, inaddition to those disclosed in the patent are either acids or acidiccompounds.

The quantity of reductone-forming catalytic agent may vary over widelimits, from less than 0.01 mole per mole of aldose sugar up to morethan equimolecular amounts based on the aldose sugar or the amineemployed. I have found that the smaller amounts provide satisfactory ofconversion is considerably lessened by using from 0.5 mole to slightlyover one mole for each mole of aldose, aldosylarnine oraminodeoxyketose. I prefer to use about equimolar proportions of acidand amine.

In the examples which follow, Examples XX, XXI, and XXII relate to atype of compound which I shall refer to asanhydro-amino-glycose-reductones. The compounds, however, are not to beconfused with anhydro or dehydrated sugar derivatives that are known inthe art. They are prepared by the elimination of 1 mole of H from themolecule of the aminoglycose-reductone. This is carried out underessentially anhydrous or nonhydrolyzing conditions, and may beaccomplished by treatment with hydrogen chloride or other dehydratingagents. The agent employed in the examples is hydrogen chloride, but anyother strongly acidic chemically dehydrating agent having an aflinityfor water may be used. I may use, for example, in the process of thesethree examples, sulfuric acid, phosphoric acid, any one of thephosphoric anhydrides, glacial acetic acid, acetic anhydride, or othercarboxylic acid anhydrides, or zinc chloride. The anhydro compounds mayalso be prepared merely by heating the hydrochloride salts of theamineglycose-reductones or their salts of other strong acids.

It is to be understood that my anhydro-reductones are not the result ofthe mere removal of water between two hydroxyl groups, or the removal ofphysically associated water in the form of moisture. Theanhydro-animoglycose-reductones have entirely different chemicalstructure from their parent compounds, even though the reductonefunction remains in the anhydro derivatives. For example, theamino-hexose-reductones, RRN'C HqOg, contain one terminal methyl groupbound to carbon. This grouping is lost during the formation of theanhydro compounds. The latter contain no such terminal methyl group.Ultra-violet absorption spectra also show a difference in structurebetween the anhydro derivative and its parent compound.

Considering the reducing sugar and the secondary amine as startingmaterials, the courses of the reaction of this invention are as follows:

Step I Step II (reducing (amine) (glycosylamine) rearrangement sugar)Step III --2H: 0 CgHuOsNRR C5H703NRR (desoxyamlnoketose)(aminoglycose-reductone) Step IV CsHaO QNRR(anhydro-aminoglycosereductonel --Hg0 C sHrO {NR R- noted; it may be acombination of steps II and III; or

it may be step III, alone.

As will be illustrated in the examples, the instances of combined stepsafford direct paths for the syntheses, and each possesses the advantagespreviously noted. Step I and step II are both catalyzed by acids; hencethe acidic reductone-forming catalyst also hastens the preliminaryreactions when it is added together with the reducing sugar and theamine at the beginning of the reaction. Furthermore, inasmuch as thereductone formation, step III, probably proceeds to a considerableextent during the progress of the rearrangement (step 11) when areductoneforming catalytic agent is present, and moreover, since step IIprobably proceeds to a considerable extent during the formation of theglycosylamine (step I) it may be seen that the combinations of stepsaffords greater net yields of reductone.

The nitrogenous reductone, which is the product of step III of thereaction as given above, consists of two separable radicals: The amineradical, -NRR, and the reductone radical, C HqOg. The two radicals whichcomprise the nitrogenous reductone can be separated by hydrolysis toyield as products: the amine, HNRR, and the nitrogen-free reductone, C HO The nitrogen-free reductone has the same strong reducing behavior inacid solution toward silver nitrate, iodine, dichlorophenolindophenol,mercuric chloride and ferric chloride as the nitrogenous reductone.Since the presence of the amine radical confers salt-like character,crystallinity and stability upon the molecule, I prefer to isolate andstore the nitrogenous compound, rather than the nitrogen-free reductone.The true reductone may be considered to be the nitrogen-free moietywhich is released upon hydrolysis, rather than the nitrogenousaminoglycose-reductone which is isolated and stored.

The nitrogen-free reductone can be liberated merely by dissolving thenitrogenous reductone in water; however, the hydrolysis may be hastenedand carried to completion by heating the aqueous mixture and/or byadding an acidic catalyst, such as hydrochloric acid, sulfuric acid,oxalic acid, picric acid, or the acid form of a cationexchange resin(see Example XIX).

Referring again to the courses of reaction characterizing thisinvention, it is practically convenient to consider steps I, II and IIIin a group, as in the foregoing paragraphs; and to consider step IVseparately. This is true, although there is a technical continuitybetween steps III and IV as will be explained subsequently.

In practice the product of step III is separated as by crystallizationor evaporation of the solution. The product is then heated underanhydrous or non-hydrolyzing conditions in the presence of the stronglyacidic chemically dehydrating agent as previously discussed.

Separation of the amino-hexose-reductone, product of step III afiordsthe elimination of sugar decomposition products by filtration. It also,of course, involves the elimination of water from the productpreparatory to step IV.

Nevertheless, steps III and IV can be carried out as a unitary step ifdesired. At the completion of the formation of theamino-hexose-reductone, anhydrous acid or acid anhydride may be added tothe reaction mixture.

Thereupon water is continuously removed from the reaction medium, andstep-IV proceeds as, the water content falls and the conditions tendtoward the anhydrous.

The foregoing procedure of step IV is not to be confused with the stepof preparing the nitrogen-free reductone previously described. Theformer (step IV), involves the removal of one mole of H 0 from thearninohexose-reductone molecule whereas the latter involves theseparation of the amine (NRR) group by hydrolysis.

This application is a continuation in part of Serial Number 405,262,filed January 20, 1954, now abandoned.

, The following specific examples illustrate the iuvention:

EXAMPLE I (a) A commercial grade of anhydrous glucose, 180 g. (1.00mole), was added in portions to 110 g. (1.30 moles) of piperidine(practical grade, B.P. 98-108") which was preheated to 65 C. and stirredmechanically in a 2-liter, 3-ne cked flask. The flask was fitted with athermometer, stirrer and removable reflux condenser.

The mixture was rapidly stirred at 65-70 C. for ten minutes, whereafterit became homogeneous due to condensation of the glucose and thepiperidine to form N-glucosylpiperidine. The amber solution was heatedten minutes longer at 70 C. to insure maximum formation ofN-glucosylpiperidine. (In previous experiments crystalline Nglucosylpiperidine was isolated from the reaction solution at this pointin 84-87 percent yield.)

The heating bath and reflux condenser were removed and with continuedstirring crystalline malonic acid, 40

'g. (0.38 mole), was added gradually over five minutes.

The solution became viscous and dark red in color; the temperature roseto. 90 C. Absolute ethanol (150 ml.) was added, thinning the pasty massand reducing the temperatureto 70 C. The heating bath and refluxcondenser were then replaced and heating was resumed. (In previousexperiments crystalline 1deoxy-1-piperidinofructose was isolated in22-30 percent yields at this stage.)

The dark red-brown solution was heated at 80 C. for ten hours;Crystallization of the reductone product began after seven hours ofheating. After cooling the flask at 0 C. for two days the crystallineproduct was filtered oil? and washed with ethanol and acetone; yield 40g., tancolored crystals, M.P. 230-232 C. with slow decomposition above210 C.

The filtrate with the washingsfrom the first crop of crystals was heatedat 90-95 C. on the steam pot for eight hours, during which time most ofthe solvent was evaporated. After cooling at 0 C. a second crop ofcrystals, 4 g., M.P. 228-230 C. with decomposition, was obtained. Thetotal yield was 44 g. or 21 percent of the amounttheoretically possiblefrom one mole of glucose.

The product was recrystallized from 3 liters of boiling absolutealcohol, yielding 36 g. of nearly white crystals, M.P. 230-232 C. withdecomposition.

Analysis of the recrystallized product gave 62.6 percent C, 8.08 percentH, 6.59 percent N; calculated for C11H17O3NI 62.5 percent C, 8.11percent H, 6.63 percent N. The molecular weight, as determined inmethanol by the Signer method, was 239; calculated for C H O 211. Byiodine titration of a solution of the compound in dilute acetic acidheld under a nitrogen atmosphere, the molecular weight (calculated onthe basis of two equivalents of iodine consumed per mole of compound)was 211. Acidic solutions of the compound also reduced silver, mercuricand ferric salts, as well as 2,6- dichlorophenolindophenol (twoequivalents per mole). This strong, quantitative reducing behaviorclassifies the organic compound as a reductone, namelypiperidinoh'exose-reductone.

A saturated aqueous solution of piperidino-hexosereductone (0.25percent) was neutral (pH 6) and optical- 1y inactive.- I It showsmaximum light absorption inthe in the compound.

Piperidino-hexose-reductone, C H O N, gave a mono- O-methyl etherderivative, C H O N, M.P. 143-144 C.;

a di-O-mcthyl ether derivative, C H O N, M.P. '58- 59.5 C.; and amono-O-acetyl ester derivative,

M.P. 169 C. These derivatives did not reducing power in neutralsolutions.

(12) To obtain a derivative of piperidino-hexosereductone which wasextensively soluble in water, without loss of the reductone reducingpower, -it Was converted to the hydrochloride salt as follows:Piperidino-hexosereductone, 211 g. (1.00 mole), was completely dissolvedin 1,500 ml. of n-butanol which contained 10% hydrogen chloride byweight. After 5 minutes at 25 C., precipitation of the hydrochloridebegan. After standing for 18 hours at 25 C., the crystalline precipitatewas filtered off, washed with n-butanol and ether until colorless, thendried in a vacuum desiccator over anhydrous calcium chloride. Yield 217g., 88 percent of theory, M.P. 153- 163 C. with decomposition. Theaqueous solution of this compound was strongly acidic and reduced2,6-dichlorophenolindophenol solution very quickly at 25 C.

possess reductone On dissolving the product in water and addingbasicEXAMPLE II Anhydrous glucose, 90 g. (0.50 mole), was stirred withabsolute ethanol ml.) under an atmosphere of nitrogen in a one-literflask fitted as described in Example I. mole), was added and the mixturewas stirred at 70-75" C. for a period of one-half to one hour until allthe glucose was dissolved and a clear, golden-yellow solution wasproduced.

Glacial acetic acid, 39 g. (0.65 mole), was dissolved in absoluteethanol (50 ml.) and the mixed solution was added dropwise to thegolden-yellow solution over a period of twenty minutes. The color of thereaction solution changed to a deep red during the addition of acid.After heating the clear, red solution under nitrogen and under reflux at75 C. for six hours, seed crystals of the crystalline reductone, C H ON, obtained as described in Example I, were added. The product thencrystallized from the reaction mixture (now a dark red brown,caramel-like color) on further heating.

After a total of twelve hours of heating at 75 C., the reaction mixturewas cooled and kept at 0 C. for one day, then filtered. The crystalswere washed with ethanol on the filter until free of adhering motherliquor, then dried in a vacuum desiccator over anhydrous calciumchloride. The yield was 28 g., or 27 percent of the amount theoreticallypossible from 0.50 mole of glucose. The crystals melted at 229-232 C.with decomposition, reduced exactly two equivalents of iodine per mole(calculated for a molecular weight of 211.3 and titrated in 0.02 Nacetic acid solution), and was identical in all properties with thereductone compound, C H O N, described in Example I. a r

The mother liquor from the above product was concentrated in a vacuum(20 mm.) at 35 C. until no'more distillate was obtained. The thick,sirupy residue was then heated at 85 C. under reflux for six hours. Uponseeding, cooling to 0 C., filtering, washing and drying, 4 g. more ofthe same compound, C H O,N,'M.P.

Piperidine (B.P. -107 C.), 55 g. (0.65

229-232 C. with decomposition, was obtained. The total yield wastherefore 32 g., or 30 percent of the theoretical amount.

The experiment was repeated six times (Expts. 1-6) as described abovewith variation only in the amount of glacial acetic acid added. In threeother experiments (Nos. 7-9) the amounts of piperidine, solvent and thereaction temperature were varied. The results are summarized in thefollowing table:

Table I Glacial Acetic Acid Yield of reduc- Added tone isolated after 12hours Expt. No. heating at Moles per Moles per 75 C. percent mole ofmole of of theory based glucose plperidine on glucose) 1 Only one moleof piperidinc was added per mole of glucose. 5 No solvent (ethanol) wasadded. a The temperature was raised to 85=t3 O.

The experiment also was repeated with variation only of the type ofsugar used. The reactant concentrations and other reaction conditionswere maintained as given above. The results are recorded in Table II.

No crystalline product was isolated; however, 5 mg. of each of the finalreaction mixtures quickly reduced ml. of 0.03 percent2,6-dlchlorophenolindophenol in acetic acid solution within 10 seconds,indicating the presence of one or more reductone compounds.

EXAMPLE III The experiment described in Example 11 was repeated, exceptthat beta-mercaptopropionic acid HS CH CH COOH was used as the catalystinstead of acetic acid. Only 0.50 mole of beta-mercaptopropionic acidwas added per mole of glucose. After hours of heating at 85 C., the samereductone compound isolated in Examples I and II, C H O N, M.P. 229-232"C. with decomposition, was isolated. Yield, 11 g. The crude crystallineproduct was only pale yellow in color in contrast to the darker browncrude product which was obtained under the same conditions using malonicor acetic acid as the catalyst.

EXAMPLE IV The experiment described in Example II was repeated, exceptthat acetic anhydride (1.0 mole per mole of glucose) was used as acombination dehydrating agent and catalyst. The crystalline compoundisolated was identical in every way with that obtained in Examples 1, Hand III. Yield, 5 g.

8 EXAMPLE v The experiment described in Example 11 was repeated, exceptthat meta-phosphoric acid was used as a combination acid catalyst anddehydrating agent, instead of acetic acid. Glucose (0.50 mole),piperidine (0.65 mole), absolute ethanol ml.) and meta-phosphoric acid40 g. (ground to a powder in a mortar) were stirred together and heatedunder nitrogen and under reflux with continuous stirring for twentyhours at 75 C. The metaphosphoric acid was a commercial preparation(solid stick form) which contained approximately 35 percent HPO and 60percent sodium meta-phosphate, NaPO Hence, only 0.18 mole of HPOactually was present. After cooling and filtering the reaction mixture,75 g. of dry, crystalline solids was isolated. The solids were washedtwice with water to remove sodium phosphate, leaving 24 g. of white,phosphate-free reductone, C11H17O3N, M.P. 229232 C. with decomposition.The yield was 23 percent of the theoretical amount. Titration of thecompound in dilute acetic acid with standard iodine solution gave theexpected result: 2.00 equivalents of iodine were reduced per mole(211.3) of the compound.

EXAMPLE VI One mole of anhydrous glucose, 180 g., was heated and stirredwith one mole of piperidine, 85.5 g., in 250 ml. methanol at 70 C. untila clear yellow solution of N-D-glucosylpiperidine was obtained (20minutes). Ortho-phosphoric acid of 100 percent concentration, 39 g., 0.4mole, was then slowly added to the stirred solution. Heating wascontinued under reflux at 75 C. for 18 hours. After 8 hours acrystalline precipitate was continuously present. The mixture was cooledto 2 C., then the crystals were isolated by filtration. Yield 43 g., 20percent of theory, prismatic crystals discolored yellow.Recrystallization of the product from 24 volumes of boiling methanolgave 31 g. of nearly colorless crystals which melted with decompositionat 235 C. Calculated for piperidino-hexose-reductone, C H O N: N, 6.63;mol. wt. 211; found by analysis; N, 6.6; mol. wt. 211 (iodinetitration).

EXAMPLE VII Carbon dioxide may be used as the reductone-formingcatalyst. The experiment cited in Example VI was repeated; however,instead of adding phosphoric acid, a stream of carbon dioxide gas waspassed continuously through the reaction mixture.Piperidino-hexose-reductone, M.P. 232-233 C. with decomposition, wasisolated in 7 percent of the theoretical yield.

EXAMPLE VIII Morpholino-hexose-reductone c Hz-C H? N- C 0H7 0 a o H2- oH.

(a) The experiment described in Example II was repeated, except thatpiperidine was replaced by the less costly amine, morpholine.Morpholine, C H ON, B.P. 124-126" C., was added to the extent of 0.65mole or 1.30 moles per mole of glucose. After the addition of glacialacetic acid (0.4 mole per mole of glucose) in ethanol, the deep redreaction mixture was heated under nitrogen and under reflux for sixteenhours at 87 C. Crystallization occurred after cooling and standing at 0C. The product was isolated as described for the piperidine derivative.Yield, 29 g. (27 percent of theory, based on glucose).

Recrystallization of the product from boiling methanol (350 ml.) gave 25g. of yellow-tinged crystals, M.P. 215-216" C. with decomposition, whichwere 99.5 percent pure by iodine titration. Analysis of therecrystallized product gave 56.6 percent C, 7.05 percent H, 6.58

.but at the lower temperature of 73 I scribed in part (a),

games percent Calculated for C H O;N: 56.3 percent C 7.09 percent H,6.56 percent N. The compound, morpholino-hexose-reductone, showed thesame strong reducing behavior toward silver nitrate, iodine and 2,6-

' dichlorophenolindophenol in acidic solutions as thepiperidino-hexose-reductone which was isolated in the precedingexamples. Analysis for acetic acid, after chromic acid, oxidation by theKuhn-Roth procedure showed the presence-of one terminal methyl group ineach molecule of the morpholino-hexose-reductone.

(b) The experiment described in part (a) above was repeated, but withheating for thirty minutes only after the addition of acetic acid. Aftercooling, allowing to stand at C. for several days and re-processing the.

147-148 C. A mixture of the compound with an authentic sample of 1 deoxy1 morpholinofructose also melted at 147-148 C. Since the compound didnot reduce silver nitrate or 2,6-dichlorophenolindophenol in acidsolution, it possessed no reductone properties. However, it did reduce2,6-dichlorophenol-indophenol in dilute sodium hydroxide solution at 25C., a reducing action which is characteristic of thel-amino-l-deoxy-2-ketoses. This experiment shows that the Amadorirearrangement product is an intermediate which is formed in thereductone-producing reaction. Examples XV and XVI show that crystallinepiperidino-hexose-reductone can be formed starting with the Amadorirearrangement product, 1-

deoxy-l-piperidinofructose. 1

(c) Repetition of the experiment described in part (a),

C., gave l-deoxy-lmorpholinofructose, M.P. 147-148 C., in 37 percent ofthe theoretical yield based on glucose. 9

(d) Morpholino-hexose-reductone, prepared as dewas converted to thehydrochloride salt by'stirring one molecular equivalent in 4 to 5 partsby weight of n-butanol solutionwhich contained 9 percent by weight ofanhydrous hydrogen chloride. After heating the slurry for 5 minutes at50 to 60 C., the

crystals were filtered, washed with n-butanol and ethyl acetate, thendried in a vacuum desiccator over calcium chloride. The yield was 95percent of theory. Recrystallization from ethanol gave nearlycolorlesscrystals which melted with much decomposition at 160 C.

Calcd. for C H 0 NCl: C, 48.1; H, 6.46; N, 5.62; Cl, 14.2. Found byanalysis: C, 48.6; H, 6.42; N, 5.67; Cl. 13.9.

The product was more soluble in water thanmorpholino-hexose-reductone,yielding a strongly acidic solution whichquickly reduced 2,6-dichlorophenolindophenol at 25 C. Chromic acidoxidation gave 0.94 mole of aceticacid per. mole which demonstrated thecontinued presence ofr one terminal methyl grouping in the reduct'oneradical EXAMPLE IX Dimethylamino-hexose-reductone 7 N'OaH10s Anhydrousglucose, 720 g. (4.00 moles), was suspended in one liter of methanol and200 g. (4.44 moles) of liquid dimethylamine was added at 0 F. Glacialacetic acid, 245 g. (4.08 moles) was dropped into the reaction mixturewhile stirring continuously under an atmosphere of. nitrogen. Thetemperature rose during the acid addition and most of the glucosedissolved. The mixture was then heated by steam at the refluxtemperature of 74 C. for 25 hours. One liter of solvent was removed fromthe dark red-brown reaction mixture by vacuum distillation, whereuponcrystallization of the product anol gave 98 percent recovery (3 crops)of bright orange crystals, M.P. 2l3-2l4 C. (decomposition). I

Calcd. for C H O N: C, 56.1; H, 7.65; N, 8.18; mol.

wt., 171. Found by analysis: C, 56.4; H, 7.66; N, 8.14;

mol. wt., 172.

The crystalline product, dimethylamino-hexose-reductone, when dissolvedin dilute acetic acid, reduced two equivalents of2,6-dichlorophenolindophenol or of iodine,

at 25 C.

EXAMPLE -X Diallylamino=hexose-reductone HHH H H IiI N-CaH10a Followingthe procedure given in Example II, substituting 0.65 mole ofdiallylamine -for piperidine, a small crop of light tan crystals wasisolated in 6 percent of the theoretical yield based on glucose. Afterrecrystallization from methanol, the nearly colorless product melted atC. to 177 C. with decomposition,

Calcd. for C12H17O3NZ C, 64.6; H, 7.68; N, 6.27. Found by analysis: C,64.7; H, 7.76; N, 6.23.

The compound, diallylamino-hexose-reductone, reduced 2.02 equivalents ofiodine per mole in dilute acetic acid solution.2,6-dichlorophenolindophenol solution also was reduced rapidly to thecolorless form at 25 0., indicating the presence of a reductonestructure.

EXAMPLE XI Di-n-butylamino-hexose-reductone CHaCHzCHzCH:

N 051110 CHaCHzCHzCHz Anhydrous glucose, 180 g. (1.00 mole);di-n-butylamine, 168 g. 1.30 moles glacial acetic acid, 79 g. (1.30moles); and methanol (100 ml.) were stirred under an atmosphere ofnitrogen while heating under reflux at 85 C. for 12 hours. The darkred-brownreaction mixture was then continuously extracted with one literof pentane-hexane, B.P. 35 C. to 45 C., for 2 days.

Distillation of the petroleum ether extractyielded a sirupy residuewhich partially crystallized, after storage at 0 C. Filtration yielded8.7 g. of crude crystalline product (3.5 percent of theory based onglucose). After two recrystallizations from acetone, the crystals werecolorless, M.P. 142-143 C.

Calcd. for C H O N: C, 65.9; H, 9.87; N, 5.49; mol. I

pound.

EXAMPLE XII Piperazino-di-(hexose-reductone) CHz-CHZ N-CaH70a CHr-CHzAnhydrous glucose, 36 g. (0.20 mole); piperazine, 8.9

0 e117 0 a-N g. 98 percent pure (0.10 mole); glacial acetic acid, 12 g.(0.20 mole); and ethanol (30 ml.) were'heated togetherper mole ofcomwith mechanical stirring, under reflux and under a nitrogenatmosphere, for 22 hours at 80 C. The tan, crystalline powder whichseparated on cooling was filtered oif, washed with hot methanol andacetone, then allowed to hydrate until in equilibrium with atmospherichumidity (65 percent relative humidity). The yield was 2.3 g., 3.3percent of theory based on glucose.

Calcd. for C H O N -H O: C, 53.9; H, 6.79; N, 7.86. Found by analysis:C, 53.9; H, 6.81; N, 7.86.

The mole of water of hydration could be removed by drying in a vacuum(0.3 mm. mercury) at 100 C. The dried product was hygroscopic. Itreduced 3.8 equivalents of iodine per mole in acetic acid solution,showing the presence of two reductone (enediol-a-carbonyl) groupings incombination with the bi-functional piperazino radical.

EXAMPLE XIII Crystals of N-galactosylpiperidine g.) were allowed tostand in a screw-capped bottle for 29 months at 25 C. The crystalscoalesced to a dark-brown heterogeneous mass. The tarry mass wasextracted with 1:1 methanol-acetone, yielding as a residue 1.7 g. oftancolored crystals percent of the theoretical yield), M.P. 225-227 C.with decomposition. When the compound Was recrystallized twice frommethanol it showed the same melting point, analysis, and reducingproperties as the product described in Example I.

EXAMPLE XIV (a) Crystals of N-galactosylpiperidine (5.0 g.) were heatedin a tube in an Abderhalden drying apparatus over boiling water (98-100C.) at 0.2-0.3 mm. of mercury pressure for two hours. The crystalsslowly turned brown and coalesced to a dark red-brown residue. Theresidue was extracted with 1:1 methanol-acetone yielding 0.3 g. ofinsoluble crystalline product which was identical in all properties withthe reductone described in Example I.

(b) The experiment was repeated with N-glucosylpiperidine(piperidine-N-glucoside), heating for 4 hours at 98-100 C. Thecrystalline product was identical with that of Example I.

EXAMPLE XV EXAMPLE XVI 1-deoxy-1-piperidinofructose, 5.0 g. (20 mmoles),was suspended in absolute ethanol. Piperidine (B.P. 105-107"), 2.3 g.(27 mmoles) and glacial acetic acid, 1.6 g. (27 mmoles) were added, thenthe solution was heated under reflux for 7 hours. The dark red-brownsolution was stored at 0 C. for three days. The crystalline precipitatewas filtered ofi, washed well with ethanolacetone (1:1), then withacetone, and dried. The yield Was 0.4 g. or 9.4 percent of thetheoretical amount; M.P. 228-232 with decomposition. Afterrecrystallization from methanol, the crystals were identical in everyway with those described in Example I.

EXAMPLE XVII 12 tion was heated under reflux on the steam bath for 90minutes whereupon it became deep red-brown in color. Diethyl ether(100ml.) was added to the cooled solution and the solution was stored at0 C. for 2 months. No crystalline product was obtained. The liquor wasthen kept at 25 C. for 4 months and, after seeding with crystals of thecrystalline reductone, c11H1 -1O3II, several large prismatic crystalsformed. Yield 0.4 g. When recrystallized from ethanol the crystalsmelted at 230- 232 (with decomposition) and were identical in allproperties with the compound described in Example 1.

EXAMPLE XVIII This example consists of two parts (a) and (b) whichillustrate the reaction in the case of glucose and a primary amine and(b) an N-glucosyl derivative of a primary amine.

(a) Anhydrous glucose, 18 g. (0.10 mole), benzylamine, 13 g. (0.12mole), boric anhydride, 7.0 g. (0.10 mole) and ethanol (250 ml.) werestirred together in a flask attached to a reflux condenser and heated ona steam bath for 3 hours. Deep red-brown color soon formed and astrongly exothermic reaction took place to produce an insolublechocolate-brown product. After cooling, the product was removed byfiltration, washing with alcohol and ether and drying in a vacuum overanhydrous calcium chloride for several days. Yield, 30 g. The productwas practically insoluble in water, alcohol, acetone and ether; yetacidic suspensions of the product reduced silver nitrate,2,6-dichlorophenolindo-phenol and iodine in the manner of reductones.

(b) Dry crystals of N-glucosylmonoethanolamine, M.P. 116 C., (30 g), waskept at 25 C. in a closed bottle for 20 months. The originally whitecrystals slowly turned brown and coalesced to a dark brown tar. The tarwas extracted 4 times with a mixture of methanol (1 part by volume) andacetone (4 parts), then the residue was dissolved in methanol andprecipitated by adding acetone with stirring. After repeating theprecipitation process twice, a chocolate-brown, melanoidin-like powderwas obtained which was dried in a vacuum over anhydrous calciumchloride. Yield, 18 g. The product gave the following analyses: 50.3percent C, 7.45 percent H and 5.95 percent N. Since the startingmaterial contained only 43.1 percent C it was apparent that aspontaneous dehydration had occurred. An aqueous solution of the product(pH 6.7) reduced 2,6-dichlorophenolindophenol and acid silver nitratesolution rapidly at 25 0., indicating a reductone structure in theproduct.

EXAMPLE XIX The following example shows that the crystalline reductone,C11H17O3N, can be hydrolyzed to yield (a) piperidine and (b) anitrogen-free reductone.

(a) The crystalline reductone, C I-I O N, 0.63 g. (3 mmoles), and picricacid, 0.69 g. (3 mmoles) were dissolved in water ml.) at C. Afterheating at 85 C. for 30 minutes the solution was concentrated underreduced pressure to a small volume (5-10 ml.) whereupon crystallizationoccurred. The yellow crystals were filtered off, washed with water anddried; yield 0.60 g., M.P. 149-150 C. After recrystallization fromethanol the compound melted at 150-15l- C. An intimate mixture of therecrystallized compound with piperidine picrate (M.P. 150-151" C.)showed no lowering of the melting point. This test showed that thecompound isolated was piperidine picrate and that the originalnitrogenous reductone had been hydrolyzed to yield the amine, piperidine(C H N), as one of the products.

(b) The crystalline reductone, C H O N, 1.0 g., was heated in water (50ml.) at C. for 10 minutes. The aqueous phase remained neutral and only asmall amount of the reductone was dissolved. A teaspoonful of wetcation-exchange resin in the free acid form (Amat 25 0., showing thepresence of a reductone.

The reductone in the filtrate was precipitated as the lead salt byadding milliliters of one normal lead acetate. The lead salt wasisolated by centrifuging. After washing with dilute acetic acid andwater and drying, the yield was 0.4 g. Analysis showed that the leadsalt contained no nitrogen.

The nitrogen-free reductone was liberated from the lead salt (in aqueoussuspension) by passing in hydrogen sulfide gas. The precipitate of leadsulfide was removed and the excess hydrogen sulfide was blown out of thesolution with nitrogen gas. Titration of an aliquot of the finalacidified solution'with standard iodine showed that 70 percent of thetheoretical amount of nitrogen-free reductone, calculated as C H O waspresent.

Paper chromatography of the solution showed a single spot (indicated byits reduction of silver nitrate solution to black silver at 25 C.) whichhad travelled 40 percent of the distance travelled by the solvent front;whereas the original nitrogenous reductone gave a spot that hadtravelled 79 percent of thatdistance.

This experiment (b) has shown that the crystalline nitrogenous reductonewill yield on hydrolysis a nitrogenfreereductone to which moiety thenitrogenous reductone owes its strong reducing power.

EXAMPLE XX Anhydro-piperidino-hexose-reductone CHz-CHt CH2 N -CaH502Clair-CH Piperidino-hexose-reductone, 320 g. (1.51 moles) was suspendedin 250 ml. of n-butanol and stirred at 60 C.

A cold solution of hydrogen chloride (10% by weight) in n butanol, 1490g. (4.1 moles of hydrogen chloride), was added and the mixture washeated in a steam bath to 60 C. over a period of 10 minutes. Thereaction mixture was then held at 60-70 C. for 20 minutes longer beforecooling rapidly to 20 C. The crop of yellow crystals thus obtained wasfiltered 01f, washed with n-butanol, ethanol and ether. Finally it wasdried in vacuo over calcium chloride to constant weight. Yield 285 g.(82 percent of theory). The crystalline product decomposed from 170 to180 C.

Calcd. for C H O NCl: N, 6.10; CI, 15.4. Found by analysisz'N, 6.18; Cl,15.4. I

' Thus one mole of water had been removed from thepiperidino-hexose-reductone and one mole of hydrogen chloride had addedto the compound thereby forming the hydrochloride salt. The compound wassoluble in water, yielding a strongly acidic solution which rapidlyreduced 2,6-dichlorophenolindophenol at 25 C.

Hydrogen chloride was removed from the compound, C H O NCl, by stirring275 g. (1.20 moles) in one liter of water followed by adding a solutionof sodium acetate (1.50 moles) to the stirred slurry. A bright yellowprecipitate formed at once. After stirring for 30 minutes under anitrogen atmosphere, the yellow crystalline product was filtered off,washed with water and dried. Yield 226 g. (98 percent of theory); M.P.188191 C. Re-

' crystallization of the product from two liters of ethanol followed by.drying in a vacuum oven at 75 C. for 4 hours gave 209 g. of the purecompound, M.P. 196-197 C. with decomposition.

Calcd. for C11H15O2NZ C, 68.4; H, Found by analysis: C, 68.2; H, 7.65;N, 7.27.

The compound reduced 2,6-dichlorophenolindophenol solution rapidly at 25C. in the manner of reductones; however, upon titration with iodine, adark red-purple color soon developed which obscured the end point. Thecompound possessed an entirely difierent structure frompiperidino-hexose-reductone, because no terminal methyl. grouping wasnot present (Kuhn-Roth C-methyl anal-. ysis). Furthermore, an aqueoussolution of the compound showed maximum light absorption at 3525 A.;whereas the starting material, piperidino-hexose-reduc-. tone,C11H17O3N, showed maximum light absorption at 3085 A. Because thisdifferent type of reductone compound was formed by removal of theelements of water from piperidino-hexose-reductone, it is named anhydro-EXAMPLE XXI Anhydro-morpholino-hexos e-reductone C H2 0 H2 Following theprocedure of the preceding example, morpholinohexose-reductone (0.200mole) was heated at C. for 20 minutes in 360 ml. of n-butanol solutionwhich contained 29 g. of anhydrous hydrogen chlo ride. The hydrochlorideof the anhydro compound crystallized on cooling and was isolated in 83percent of the theoretical yield; M.P. 143-145 C. with decompositon. Bysuspending the hydrochloride compound in sodium acetate solution,red-brown crystals of the anhydro derivative, free of hydrogen chloride,were obtained, M.P. 205206 C. with decomposition.

Calcd. for C H O N: C, 61.5; H, 6.71; N, 7.18.

Found by analysis: C, 61.6; H, 6.79; N, 7.03.

EXAMPLE XXII Anhydrodimethylamino-hexos e-reductone N o .H, o 1

Following the procedure of Example XVIII,dimethylamino-hexose-reductone, 171 g. (1.00 mole) was heated in 1,200ml. of n-butanol solution which contained 8 percent (wt./vol.) ofhydrogen chloride. After heating for a total of 20 minutes at 7080 C.,the hydhochloride salt of the anhynro derivative was isolated in 80percent yield. When the crystalline hydrochloride of the anhydroderivative was suspended and stirred in sodium acetate solution, it wasconverted to the hydrogen chloride-free anhydro derivative in 72 percentof the theoretical yield. Orange crystals of M.P. 211-212 C.(decomposition) were obtained.

Calcd. for C H O N: C, 62.7; H, 7.24; N, 9.15. Found by analysis: C,63.1; H, 7.24; N, 9.00.

The product, anhydro-dimethylamino-hexose-reductone, when dissolved inaqueous acetic acid, reduced 2,6-dichlorophenolindophenol solutionrapidly at 25 C. Upon titration with iodine, a dark, red-purple colordeveloped which obscured the end point.

I claim:

1. A method for producing aminohexose reductones which comprisesheating, to a temperature of about from 60 to C. for a period of about 2to 24 hours in a reaction medium substantially free of water, a hexosereducing sugar with a secondary amine selected from the. groupconsisting of piperidine, piperazine, morpholine,

dimethylamine, diallylamine, and di-n-butylamine, said acetate,morpholine acetate, ethylamine acetate, malonic acid, piperidinemalonate, dibutylamine malonate, proprionic acid, beta-mercaptopropionicacid, benzoic acid, phthalic acid, snccinic acid, citric acid, glycine,asparagine, and glutamic acid, thereby to produce the correspondingaminohexose reductone, and recovering said aminohexose reductone fromthe reaction mixture.

2. The process of claim 1 wherein the secondary amine is piperidine.

3. The process of claim 1 wherein the secondary amine isdi-n-butylamine.

4. The process of claim 1 wherein the secondary amine is morpholine.

5. Piperidino hexose reductone.

6. Di-n-butylaminohexose reductone.

7. Morpholinohexose reductone.

8. A method for producing anhydro-aminohexose reductones which comprisesheating an aminohexose reductone produced by the process of claim 1 to atemperature of about from 60 to 100 C. for a period of about from 10minutes to 1 hour under substantially anhydrous conditions in thepresence of a strongly acidic chemically dehydrating agent to producethe corresponding anhydroaminohexose reductone, and recovering saidanhydroaminohexose reductone from the reaction mixture.

9. The process of claim 8 wherein the dehydrating agent is hydrogenchloride.

10. The method comprising suspending piperidinohexose-reductone inbutanol, adding hydrogen chloride, heating the reaction mixture andmaintaining its temperature at 60-70 C. for a period of approximately 30minutes, cooling the reaction mixture rapidly to about 16 20 C., andrecovering anhydro-piperidino-hexose-redutone from the reaction mixture.

11. The method comprising suspending morpholinoheXose-reductone inbutanol, adding hydrogen chloride, heating the reaction mixture to andmaintaining the temperature at about 80 C. for about 20 minutes, andrecovering anhydro-morpholino-hexose-reductone from the reactionmixture.

12. The method comprising suspending dimethylamino- 10 hexose-reductonein butanol, adding hydrogen chloride, heating the mixture to about 70-80C. for about 20 minutes, and recoveringanhydro-dimethylamino-hexosereductone from the reaction mixture.

13. Anhydro-amino-hexosereductone. 14.Anhydro-piperidino-hexose-reductone.

15. Anhydro-morpholino-hexose-reductone. 16.Anhydro-dimethylamino-hexose-reductone.

References Cited in the file of this patent UNITED STATES PATENTS2,197,540 Klug Apr. 16, 1940 2,354,846 Weygand Aug. 1, 1944 2,715,123Hodge Aug. 9, 1955 FOREIGN PATENTS 727,402 Germany Nov. 4, 1942 OTHERREFERENCES Fieser and Fieser: Organic Chemistry, published by Heath,Reinhold Co. (N.Y.), 1950, pp. to 57.

Wendland: Arch. Pharm., vol. 285, pp. 71-79 (1952), abstracted fromChem. Abst., vol. 46, col. 11286bde.

1. A METHOD FOR PRODUCING AMINOHEXOSE REDUCTONES WHICH COMPRISESHEATING, TO A TEMPERATURE OF ABOUT FROM 60* TO 110*C. FOR A PERIOD OFABOUT 2 TO 24 HOURS IN A REACTION MEDIUM SUBSTANTIALLY FREE OF WATER, AHEXOSE REDUCING SUGAR WITH A SECONDARY AMINE SELECTED FROM THE GROUPCONSISTING OF PIPERIDINE, PIPERAZINE, MORPHOLINE, DIMETHYLAMINE,DIALLYLAMINE, AND DI-N-BUTYLAMINE, SAID HEATING TAKING PLACE IN THEPRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF PHOSPHORICACID, BORIC ACID, CARBONIC ACID, ACETIC ACID, ACETIC ANHYDRIDE,PIPERIDINE ACETATE, MORPHOLINE ACETATE, ETHYLAMINE ACETATE, MALONICACID, PIPERIDINE MALONATE, DIBUTYLAMINE MALONATE, PROPIONIC ACID,BETA-MERCAPTOPROPIONIC ACID, BENZOIC ACID, PHTHALIC ACID, SUCCINI ACID,CITRIC ACID, GLYCINE, ASPARAGINE, AND GLUTAMIC ACID, THEREBY TO PRODUCETHE CORRESPONDING AMINOHEXOSE REDUCTONE, AND RECOVERING SAID AMINOHEXOSEREDUCTONE FROM THE REACTION MIXTURE.
 6. DI-N-BUTYLAMINOHEXOSE REDUCTONE.8. A METHOD FOR PRODUCING ANHYDRO-AMINOHEXOSE REDUCTONES WHICH COMPRISESHEATING AN AMINOHEXOSE REDUCTONE PRODUCED BY THE PROCESS OF CLAIM 1 TO ATEMPERATURE OF ABOUT FROM 60* TO 100*C. FOR A PERIOD OF ABOUT FROM 10MINUTES TO 1 HOUR UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS IN THEPRESENCE OF A STRONGLY ACIDIC CHEMICALLY DEHYDRATING AGENT TO PRODUCETHE CORRESPONDING ANHYDROAMINOHEXOSE REDUCTONE, AND RECOVERING SAIDANHYDROAMINOHEXOSE REDUCTONE FROM THE REACTION MIXTURE. 13.ANHYDRO-AMINO-HEXOSE-REDUCTONE.